The real world is not binary. In fact, not even the digital world is binary: https://en.wikipedia.org/wiki/Ternary_computer

Valid reasons exist for verifying the user age and only provide access/services to humans above a given age, and at same time this can be done without revealing my children details to some megacorp that will store those details forever (privacy).

When you are facing two bad choices you must start by questioning why the heck there are only two choices in the first place. That is the first step you take outside those manipulation techniques for the masses.